Optimization Design of the Multi-Layer Cross-Sectional Layout of An Umbilical Based on the GA-GLM

Marine umbilical is one of the key equipment for subsea oil and gas exploitation,which is usually integrated by a great number of different functional components with multi-layers.The layout of these components directly affects manufacturing,operation and storage performances of the umbilical.For the multi-layer cross-sectional layout design of the umbilical,a quantifiable multi-objective optimization model is established according to the operation and storage requirements.Considering the manufacturing factors,the multi-layering strategy based on contact point identification is introduced for a great number of functional components.Then,the GA-GLM global optimization algorithm is proposed combining the genetic algorithm and the generalized multiplier method,and the selection operator of the genetic algorithm is improved based on the steepest descent method.Genetic algorithm is used to find the optimal solution in the global space,which can converge from any initial layout to the feasible layout solution.The feasible layout solution is taken as the initial value of the generalized multiplier method for fast and accurate solution.Finally,taking umbilicals with a great number of components as examples,the results show that the cross-sectional performance of the umbilical obtained by optimization algorithm is better and the solution efficiency is higher.Meanwhile,the multi-layering strategy is effective and feasible.The design method proposed in this paper can quickly obtain the optimal multi-layer cross-sectional layout,which replaces the manual design,and provides useful reference and guidance for the umbilical industry.

Wideband radar cross-section reduction by a double-layer-plasma-based metasurface

Reduction of the radar cross-section(RCS) is the key to stealth technology. To improve the RCS reduction effect of the designed checkerboard metasurface and overcome the limitation of thinlayer plasma in RCS reduction technology, a double-layer-plasma-based metasurface—composed of a checkerboard metasurface, a double-layer plasma and an air gap between them—was investigated. Based on the principle of backscattering cancellation, we designed a checkerboard metasurface composed of different artificial magnetic conductor units;the checkerboard metasurface can reflect vertically incident electromagnetic(EM) waves in four different inclined directions to reduce the RCS. Full-wave simulations confirm that the doublelayer-plasma-based metasurface can improve the RCS reduction effect of the metasurface and the plasma. This is because in a band lower than the working band of the metasurface, the RCS reduction effect is mainly improved by the plasma layer. In the working band of the metasurface,impedance mismatching between the air gap and first plasma layer and between first and second plasma layers cause the scattered waves to become more dispersed, so the propagation path of the EM waves in the plasma becomes longer, increasing the absorption of the EM waves by the plasma. Thus, the RCS reduction effect is enhanced. The double-layer-plasma-based metasurface can be insensitive to the polarization of the incoming EM waves, and can also maintain a satisfactory RCS reduction band when the incident waves are oblique.

Dyslipidemia in Adults with Type 2 Diabetes in a Rural Community in Ganadougou, Mali: A Cross-Sectional Study

Dyslipidemia is a disorder where abnormally lipid concentrations circulate in the bloodstream. The disorder is common in type 2 diabetics (T2D) and is linked with T2D comorbidities, particularly cardiovascular disease. Dyslipidemia in T2D is typically characterized by elevated plasma triglyceride and low high-density lipoprotein cholesterol (HDL-C) levels. There is a significant gap in the literature regarding dyslipidemia in rural parts of Africa, where lipid profiles may not be captured through routine surveillance. This study aimed to characterize the prevalence and demo-graphic profile of dyslipidemia in T2D in the rural community of Ganadougou, Mali. We performed a cross-sectional study of 104 subjects with T2D in Ganadougou between November 2021 and March 2022. Demographic and lipid profiles were collected through cross-sectional surveys and serological analyses. The overall prevalence of dyslipidemia in T2D patients was 87.5% (91/104), which did not differ by sex (P = .368). High low-density lipoprotein cholesterol (LDL-C) was the most common lipid abnormality (78.9%, [82/104]). Dyslipidemia was associated with age and hypertension status (P = .013 and.036, respectively). High total and high LDL-C parameters were significantly associated with hypertension (P = .029 and .006, respectively). In low-resource settings such as rural Mali, there is a critical need to improve infrastructure for routine dyslipidemia screening to guide its prevention and intervention approaches. The high rates of dyslipidemia observed in Gandadougou, consistent with concomitant increases in cardiovascular diseases in Africa suggest that lipid profile assessments should be incorporated into routine medical care for T2D patients in African rural settings.

Association between triglyceride-glucose index and colorectal polyps:A retrospective cross-sectional study

BACKGROUND Colorectal polyps(CPs)are frequently occurring abnormal growths in the colorectum,and are a primary precursor of colorectal cancer(CRC).The triglyceride-glucose(TyG)index is a novel marker that assesses metabolic health and insulin resistance,and has been linked to gastrointestinal cancers.AIM To investigate the potential association between the TyG index and CPs,as the relation between them has not been documented.METHODS A total of 2537 persons undergoing a routine health physical examination and colonoscopy at The First People's Hospital of Kunshan,Jiangsu Province,China,between January 2020 and December 2022 were included in this retrospective cross-sectional study.After excluding individuals who did not meet the eligibility criteria,descriptive statistics were used to compare characteristics between patients with and without CPs.Logistic regression analyses were conducted to determine the associations between the TyG index and the prevalence of CPs.The TyG index was calculated using the following formula:Ln[triglyceride(mg/dL)×glucose(mg/dL)/2].The presence and types of CPs was determined based on data from colonoscopy reports and pathology reports.RESULTS A nonlinear relation between the TyG index and the prevalence of CPs was identified,and exhibited a curvilinear pattern with a cut-off point of 2.31.A significant association was observed before the turning point,with an odds ratio(95% confidence interval)of 1.70(1.40,2.06),P<0.0001.However,the association between the TyG index and CPs was not significant after the cut-off point,with an odds ratio(95% confidence interval)of 0.57(0.27,1.23),P=0.1521.CONCLUSION Our study revealed a curvilinear association between the TyG index and CPs in Chinese individuals,suggesting its potential utility in developing colonoscopy screening strategies for preventing CRC.

Mental health and insomnia problems in healthcare workers after the COVID-19 pandemic:A multicenter cross-sectional study

BACKGROUND Healthcare workers(HCWs)are at increased risk of contracting coronavirus disease 2019(COVID-19)as well as worsening mental health problems and insomnia.These problems can persist for a long period,even after the pandemic.However,less is known about this topic.AIM To analyze mental health,insomnia problems,and their influencing factors in HCWs after the COVID-19 pandemic.METHODS This multicenter cross-sectional,hospital-based study was conducted from June 1,2023 to June 30,2023,which was a half-year after the end of the COVID-19 emergency.Region-stratified population-based cluster sampling was applied at the provincial level for Chinese HCWs.Symptoms such as anxiety,depression,and insomnia were evaluated by the Generalized Anxiety Disorder-7,Patient Health Questionnaire-9,and Insomnia Severity Index.Factors influencing the symptoms were identified by multivariable logistic regression.RESULTS A total of 2000 participants were invited,for a response rate of 70.6%.A total of 1412 HCWs[618(43.8%)doctors,583(41.3%)nurses and 211(14.9%)nonfrontline],254(18.0%),231(16.4%),and 289(20.5%)had symptoms of anxiety,depression,and insomnia,respectively;severe symptoms were found in 58(4.1%),49(3.5%),and 111(7.9%)of the participants.Nurses,female sex,and hospitalization for COVID-19 were risk factors for anxiety,depression,and insomnia symptoms;moreover,death from family or friends was a risk factor for insomnia symptoms.During the COVID-19 outbreak,most[1086(76.9%)]of the participating HCWs received psychological interventions,while nearly all[994(70.4%)]of them had received public psychological education.Only 102(7.2%)of the HCWs received individual counseling from COVID-19.CONCLUSION Although the mental health and sleep problems of HCWs were relieved after the COVID-19 pandemic,they still faced challenges and greater risks than did the general population.Identifying risk factors would help in providing targeted interventions.In addition,although a major proportion of HCWs have received public psychological education,individual interventions are still insufficient.

Patterns of Infertility and Abortion in Saudi Arabia: A Cross-Sectional Study

Background: Infertility and abortion are significant reproductive health concerns globally, impacting individuals' well-being and healthcare systems. In Saudi Arabia, cultural, social, and religious factors influence perceptions and management of these issues, necessitating research to understand the patterns and associated factors. Study Aim: This cross-sectional study aimed to investigate the patterns of infertility and abortion among 458 women in Saudi Arabia, focusing on demographic profiles, reproductive histories, medical conditions, and lifestyle factors. Methodology: Participants were recruited from healthcare facilities, and data on age, BMI, reproductive history, medical conditions, assisted reproduction methods, and lifestyle behaviors were collected. Statistical analyses, including chi-square tests, were conducted to examine associations between variables. Results: The majority of participants were aged 30 - 39 years (47.4%), with 76.9% experiencing secondary infertility. Among those with offspring (76.9%), 31% reported using assisted reproduction methods, primarily ovarian stimulators (54.2%). Abortion history was reported by 39.5% of participants. Significant associations were found between age and infertility type (X2 = 5.8, p = 0.054), having offspring and infertility type (X2 = 458.0, p = 0.001), menstrual irregularity and infertility type (X2 = 11.4, p = 0.001), and abortion history and delayed fertility (X2 = 10.4, p = 0.001). Conclusion: Our study reveals significant associations between demographic, medical, and lifestyle factors with infertility patterns and abortion history among Saudi women. These findings emphasize the need for tailored interventions addressing medical conditions, age-related factors, and access to reproductive healthcare services.

Theoretical analysis of the double-differential cross-sections of neutron,proton,deuteron,^(3)He,andαfor the p+^(6) Li reaction

Based on the unified Hauser–Feshbach and exciton model,which can describe the particle emission processes between discrete energy levels with energy,angular momentum,and parity conservations,a statistical theory of light nucleus reaction(STLN)is developed to calculate the double-differential cross-sections of the outgoing neutron and light charged particles for the proton-induced^(6) Li reaction.A significant difference is observed between the p+^(6) Li and p+^(7) Li reactions owing to the discrepancies in the energy-level structures of the targets.The reaction channels,including sequential and simultaneous emission processes,are analyzed in detail.Taking the double-differential cross-sections of the outgoing proton as an example,the influence of contaminations(such as^(1) H,^(7)Li,^(12)C,and^(16)O)on the target is identified in terms of the kinetic energy of the first emitted particles.The optical potential parameters of the proton are obtained by fitting the elastic scattering differential cross-sections.The calculated total double-differential cross-sections of the outgoing proton and deuteron at E_(p)=14 MeV agree well with the experimental data for different outgoing angles.Simultaneously,the mixed double differential cross-sections of^(3) He andαare in good agreement with the measurements.The agreement between the measured data and calculated results indicates that the two-body and three-body breakup reactions need to be considered,and the pre-equilibrium reaction mechanism dominates the reaction processes.Based on the STLN model,a PLUNF code for the p+^(6) Li reaction is developed to obtain an ENDF-6-formatted file of the double-differential cross-sections of the nucleon and light composite charged particles.

Association of total bilirubin with depression risk in adults with diabetes:A cross-sectional study

BACKGROUND Individuals with diabetes mellitus are more likely to experience depression,although most patients remain undiagnosed.The relation between total bilirubin and depression has been increasingly discussed,but limited studies have examined the association of total bilirubin with depression risk in adults with diabetes,which warrants attention.AIM To investigate the association between total bilirubin levels and the risk of depression in adults with diabetes.METHODS The study included adults with diabetes from the National Health and Nutrition Examination Survey 2007-2018.Depression was determined using the Patient Health Questionnaire-9.Multivariable logistic regression,propensity scorematched analysis and restricted cubic spline models were utilized to investigate the association between total bilirubin levels and depression risk in adults with diabetes.RESULTS The study included 4758 adults with diabetes,of whom 602(12.7%)were diagnosed with depression.After adjusting for covariates,we found that diabetic adults with lower total bilirubin levels had a higher risk of depression(OR=1.230,95%CI:1.006-1.503,P=0.043).This association was further confirmed after propensity score matching(OR=1.303,95%CI:1.034-1.641,P=0.025).Subgroup analyses showed no significant dependence of age,body mass index,sex,race or hypertension on this association.Restricted cubic spline models displayed an inverted U-shaped association of total bilirubin levels with depression risk within the lower range of total bilirubin levels.The depression risk heightened with the increasing levels of total bilirubin,reaching the highest risk at 6.81μmol/L and decreasing thereafter.CONCLUSION In adults with diabetes,those with lower levels of total bilirubin were more likely to have depressive symptoms.Serum total bilirubin levels may be used as an additional indicator to assess depression risk in adults with diabetes.

Dietary fiber intake and its association with diabetic kidney disease in American adults with diabetes:A cross-sectional study

BACKGROUND Dietary fiber(DF)intake may have a protective effect against type 2 diabetes(T2D);however,its relationship with diabetic kidney disease(DKD)remains unclear.AIM To investigate the potential association between DF intake and the prevalence of DKD in individuals diagnosed with T2D.METHODS This cross-sectional study used data from the National Health and Nutrition Examination Survey collected between 2005 and 2018.DF intake was assessed through 24-h dietary recall interviews,and DKD diagnosis in individuals with T2D was based on predefined criteria,including albuminuria,impaired glomerular filtration rate,or a combination of both.Logistic regression analysis was used to assess the association between DF intake and DKD,and comprehensive subgroup and sensitivity analyses were performed.RESULTS Among the 6032 participants,38.4%had DKD.With lower DF intake-T1(≤6.4 g/1000 kcal/day)-as a reference,the adjusted odds ratio for DF and DKD for levels T2(6.5-10.0 g/1000 kcal/day)and T3(≥10.1 g/1000 kcal/day)were 0.97(95%CI:0.84-1.12,P=0.674)and 0.79(95%CI:0.68-0.92,P=0.002),respectively.The subgroup analysis yielded consistent results across various demographic and health-related subgroups,with no statistically significant interactions(all P>0.05).CONCLUSION In United States adults with T2D,increased DF intake may be related to reduced DKD incidence.Further research is required to confirm these findings.

First Born Double Differential Cross-Section for Ionization of H (3d) by Incident Electron Impact

Double differential cross section (DDCS) of First-Born approximation is calcu-lated for the ionization of metastable 3d-state hydrogen atoms by electron impact energy at 150 eV and 250 eV. A multiple scattering theory is applied in the present study. The present results are compared with the other related the-oretical results for the ionization of hydrogen atoms from different metastable states and ground-state experimental results. The findings demonstrate a strong qualitative agreement with the existing results. The obtained results have an extensive scope for further study of such an ionization process.

A Cross-Sectional Study on The Prevalence of Anemia in Maintenance Hemodialysis and Peritoneal Dialysis Patients and Its Related Factors

Objective:To study the prevalence of anemia,the proportion of hemoglobin(Hb)levels,the treatment methods,and the influencing factors of Hb levels in maintenance hemodialysis(MHD)and peritoneal dialysis patients.Methods:In this study,602 patients with maintenance hemodialysis and continuous ambulatory peritoneal dialysis were enrolled from December 2020 to December 2022 in our hospital,and their medical records were collected and summarized.The main contents included the patient’s gender,age,primary disease,dialysis duration,dialysis method,the use of erythropoietic stimulating agents(ESA),intravenous iron,and laboratory tests.A Hb index exceeding 110 g/L was set as the standard for the prevalence of anemia.Results:The rate of anemia in patients undergoing blood purification was 83%.The proportion of ESA use was 84.1%,and the proportion of iron use was 76.7%,of which the proportion of intravenous iron used was 17.0%,and the proportion of folic acid used was 28.3%.Conclusion:The incidence of anemia in MHD patients was relatively high,with a low proportion of patients reaching the standard Hb levels.Risk factors include albumin(ALB)levels,iron storage,white blood cells,C-reactive protein,cholesterol,etc.Nutritional support,iron supplementation,and prevention of micro-inflammatory reactions can effectively promote the improvement of Hb indicators in dialysis patients to prevent anemia.

Exercise, Depression, and Anxiety in Young People: A Cross-Sectional Survey

Background:Depression and anxiety are highly prevalent among adolescents and have multiple negative effects on their physical and mental health.While exercise can reduce the symptoms of depression and anxiety,the rela-tionship between mental disorders among American university students has been rarely reported.Accordingly,this study aimed to explore the association between exercise,depression and anxiety among American university students in the 2018–2019 academic year.Methods:In this cross-sectional study,the association between exercise,depression and anxiety was investigated in a large representative sample of American university students.In the 2018–2019 academic year,university students aged 18+years old from 79 institutions participated in this school-based study.The questionnaire included measurements of demographic characteristics,exercise,and validated screen instructions for depression(PHQ-9)and anxiety(GAD-7).The multivariable logistic regression model was applied to explore the association between exercise,depression and anxiety.Results:A total of 62026 indivi-duals(31.9%males)participated in this survey,and the prevalence of exercising at least 5 h each day was 24.6%.The prevalence of depression and anxiety was 25.7%and 22.3%,respectively.In the multivariable logistic regres-sion model,compared to exercise at least 5 h daily,participants whose exercise less than 1 h daily(OR=1.31[1.29,1.33],p<0.05),2 to 3 h daily(OR=1.13[1.11,1.15],p<0.05),3 to 4 h daily(OR=1.04[1.02,1.06],p<0.05),were correlated with greater odds of depression,while exercise less than 1 h daily(OR=1.23[1.21,1.25],p<0.05),2 to 3 h daily(OR=1.10[1.08,1.12],p<0.05)were significantly correlated with great-er odds of anxiety.Conclusion:Higher levels of exercise are associated with lower risk of depression and anxiety among American university students.Community and school interventions should focus on increasing exercise participation in university populations to promote both physical and mental health.

Perceived barriers and facilitators of day-case surgery for major foot and ankle procedures?A cross-sectional survey of United Kingdom surgeons

BACKGROUND Advances in minimally invasive surgery and improved post-operative pain management make it possible to consider performing even major foot/ankle operations as day-case.This could have significant benefits for patients and the health service.However there are theoretical concerns about post-operative complications and patient satisfaction due to pain.AIM To scope the current practice of foot and ankle surgeons on day-case surgery for major foot and ankle procedures in the United Kingdom(UK).METHODS An online survey(19 questions)was sent to UK foot and ankle surgeons via the British Orthopaedic Foot&Ankle Society membership list in August 2021.Major foot and ankle procedures were defined as surgery that is usually performed as an inpatient in majority of centres and day-case as same day discharge,with day surgery as the intended treatment pathway.RESULTS 132 people responded to the survey invitation with 80%working in Acute NHS Trusts.Currently 45%of respondents perform less than 100 day-case surgeries per year for these procedures.78%felt that there was scope to perform more procedures as day-case at their centre.Post-operative pain(34%)and patient satisfaction(10%)was not highly measured within their centres.Lack of adequate physiotherapy input pre/post-operatively(23%)and lack of out of hours support(21%)were the top perceived barriers to performing more major foot and ankle procedures as day-case.CONCLUSION There is consensus among UK surgeons to do more major foot/ankle procedures as day-case.Out of hours support and physiotherapy input pre/post-op were perceived as the main barriers.Despite theoretical concerns about post-operative pain and satisfaction this was only measured by a third of those surveyed.There is a need for nationally agreed protocols to optimise the delivery of and measurement of outcomes in this type of surgery.At a local level,the provision of physiotherapy and out of hours support should be explored at sites where this is a perceived barrier.

Ecological correlates of sport and exercise participation among Thai adolescents:A hierarchical examination of a cross-sectional population survey

Background:Understanding factors influencing adolescents’ sport/exercise participation(S/EP) is vital to developing effective interventions,but currently,evidence from less developed countries is limited.The purpose of this study was to examine correlates of S/EP across individual,interpersonal,and environmental levels in a nationally representative sample of Thai adolescents.Methods:Data from 4617 Thai adolescents aged 14-17 years old were obtained from recruited schools across Thailand.Data on S/EP(outcome variable),and psychosocial,home,and community environment covariates were collected from individual adolescents using the Thailand Physical Activity Children Survey,Student Questionnaire.School environmental data were collected at the school level using a School Built Environment Audit.Hierarchical regressions taking into account school clustering effects were applied for data analysis.Results:At the individual level,age and body mass index were independently and strongly correlated with S/EP.Adolescents with high preference for physical activity(PA)(odd ratio(OR)=1.71,p <0.001) and at least a moderate level of self-efficacy(OR=1.33,p=0.001) were more likely to have high S/EP.At the interpersonal level,adolescents whose parents joined their sports/exercise at least 1-2 times/week(OR=1.36,p=0.003) received>3 types of parental support(OR=1.43,p=0.005) and who received siblings’(OR=1.26,p=0.004) and friends’(OR=1.99,p <0.001) support had a greater chance of high S/EP.At the environmental level,adolescents’ S/EP was greater when there were at least 3-4 pieces of home sport/exercise equipment(OR=2.77,p=0.003),grass areas at school(OR=1.56,p <0.001),and at least 1-2 PA facilities in the community(OR=1.30,p=0.009).Conclusion:Multiple factors at different levels within an ecological framework influencing Thai adolescents’ S/EP were generally similar to those found in developed countries,despite some differences.For those interested in promoting and supporting Thai adolescents’ engagement in sports/exercise,further exploration of the influence of self-efficacy and attitude toward PA is required at the individual level;parental and peer support at the interpersonal level;and home sport equipment,school grass areas,and neighborhood PA facilities at the environment level.

A Cross-sectional Survey Assessing Carriage of Streptococcus pneumoniae in a Healthy Population in Xinjiang Uygur Autonomous Region of China

The carriage rate and serotype distribution of Streptococcus pneumoniae（S.pneumoniae）in a healthy population in China remains unclear.In this study,we collected the oropharyngeal swabs from513 individuals in Xinjiang,China.Real-time PCR targeting the lytA gene and 12 serotypes were assessed to identify S.pneumoniae carriage.

Prediction models of the ionization coefficient and ionization cross-section based on multi-layer molecular parameters

Prediction models were proposed to estimate the reduced Townsend ionization coefficient and ionization cross-section.A shape function of the reduced Townsend ionization coefficient curves was derived from the ionization collision probability model.The function had three parameters:the first ionization potential energy,A_(α),and B_(α).A_(α)and B_(α)were related to the molecule symmetry and size.The polarization of molecules could characterize the molecule symmetry.The multi-layer molecular cross-section(MMCS)was proposed to describe the contributions of electrons and molecule radius on different molecule surfaces to collisions.A prediction model of the ionization cross-section was also proposed based on Aα.The molecule parameters were calculated by the Becke3–Lee–Yang–Parr(B3LYP)method and the 6–311G**basis set.We used available data of 30 and 23 gases,respectively,to build the prediction models of reduced Townsend ionization coefficients and ionization cross-sections.The relationships between the molecular parameters Aαand Bαand the ionization cross-section were built up via nonlinear fittings.The determination coefficients R^(2)of Aα,Bα,and the ionization cross-section were 0.877,0.887,and 0.838,respectively.The results showed that the accuracy of models was positively correlated with the molecule symmetry and reduced electric field.This was mainly related to the accuracy of the MMCS model in predicting Aα.The MMCS model needed to be improved to describe the collision direction selectivity caused by the molecule asymmetry.Under a high reduced electric field,that error of Aαhad less influence on the prediction results.However,the prediction results for single atoms with high symmetry were poor.This may be due to the absolute error of the model close to single atoms’reduced Townsend ionization coefficients.The models could provide the basis for gas insulation prediction and discharge calculations,especially for symmetric molecules under a high electric field.

Direct measurement of an energy-dependent single-event-upset cross-section with time-of-flight method at CSNS

To predict the soft error rate for applications, it is essential to study the energy dependence of the single-event-upset(SEU) cross-section. In this work, we present a direct measurement of the SEU cross-section with the Back-n white neutron source at the China Spallation Neutron Source. The measured cross section is consistent with the soft error data from the manufacturer and the result suggests that the threshold energy of the SEU is about 0.5 Me V, which confirms the statement in Iwashita’s report that the threshold energy for neutron soft error is much below that of the(n, α) cross-section of silicon.In addition, an index of the effective neutron energy is suggested to characterize the similarity between a spallation neutron beam and the standard atmospheric neutron environment.

Awareness of and attitudes towards infertility and its treatment： a cross-sectional survey of men in a United States primary care population

Previous studies have described racial and socioeconomic disparities in the treatment of infertility. Patient factors such as attitudes and awareness may be contributing factors. Since primary care is often the setting that serves as an entry into other areas of medicine, we sought to evaluate men＇s attitudes and awareness of male infertility in the primary care setting. To do this, we performed a cross-sectional survey of men＇s attitudes toward men＇s health issues in 210 men from two primary care clinic waiting rooms in Atlanta, Georgia. The survey was self-administered with closed-ended question items and was approximately 20 min in length. Of the 310 men approached, 210 agreed to participate and returned completed surveys. Overall, 52% of men said they were ＂very＂ or ＂somewhat＂ familiar with infertility and 25% were familiar with treatments for infertility. Some men had heard of surgery （21%） and medication （35%） as treatments for male infertility. Awareness and familiarity with the condition was greater in high socioeconomic status men （i.e. college graduates or those with income 〉$100 k per year） but did not differ by race on multivariate analysis. Attitudes toward infertility varied by race with non-Caucasian men being more likely to indicate that infertility is a serious condition, to be concerned about infertility, and to believe it decreases a man＇s quality-of-life. Therefore, a lack of awareness, but not negative attitudes, may contribute to previously-described disparities in the treatment of infertility.

Nonfatal Child Pedestrian Injury in Two Urban Cities of Guangdong Province,China:Results from a Cross-sectional Survey

Objective To describe the epidemiological characteristics of nonfatal child pedestrian injuries and provide information to help understand an important public-health problem.Methods This was a school-based,cross-sectional questionnaire survey.The sample （42 750 children） was obtained from two urban cities of Guangdong Province,China,using multi-stage randomized sampling.Information was collected by the respondents self-reporting in the classroom.Results The incidence rate of nonfatal child pedestrian injuries in the cities was 2.0%.Boys had a higher incidence rate （2.6%） than girls （1.4%）.Compared to other children,those aged 10 years are at the highest risk.The primary places of occurrence were sidewalks,residential roads,and crosswalks.High-risk behavior of the children immediately prior to injury included mid-block crossings,playing on roads,and crossing on red lights.The major vehicles that caused pedestrian injuries were bicycles,car or vans,and motorcycles.Bruises,fractures,and injuries to the internal organs were the top three types of injuries.Almost 40% of victims were hospitalized,and nearly 30% of the victims suffered long-term disabilities.Conclusion This study shows that nonfatal child pedestrian injuries are a very serious public-health problem in the urban cities of Guangdong.Based on the epidemiological characteristics,prevention strategies and further research should be carried out to reduce the occurrence of injuries.

Large eddy simulation of supersonic flow in ducts with complex cross-sections

Large Eddy Simulation(LES)has been employed for the investigation of supersonic flow characteristics in five ducts with varying cross-sectional geometries.The numerical results reveal that flow channel configurations exert a considerable influence on the mainstream flow and the near-wall flow behavior.In contrast to straight ducts,square-to-circular and rectangular-to-circular ducts exhibit thicker boundary layers and a greater presence of vortex structures.Given the same inlet area,rectangular-to-circular ducts lead to higher flow drag force and total pressure loss than square-to-circular ducts.Characterized by the substantial flow separation and shock waves,the"S-shaped duct shows significant vertically-asymmetric characteristics.